Generally, a touch device comprises a touch screen. By touching the touch screen with the user's finger, the touch device is operated to execute a corresponding function. The widely-used touch device includes for example a smart phone, a tablet computer, a personal digital assistant (PDA), a navigation device, or the like. When the user operates the touch device by touching the touch screen with the finger, the fingerprint is usually retained on the touch screen. The fingerprint may hinder the user from viewing the touch screen.
For solving the above drawbacks, a touch pen is introduced into the market. By holding the touch pen and tapping the touch pen on the touch screen, the touch device can be operated while maintaining the cleanness of the touch screen. Moreover, for most of the touch devices, a handwriting input interface is provided for allowing the user to input characters in a handwriting manner. Since the way of inputting characters by using the touch pen is similar to the common handwriting way, the use of the touch pen to input characters may facilitate the user to input characters in the handwriting manner.
However, after the touch pen is used, the user may usually place the touch pen at random. Consequently, the possibility of losing the touch pen is very high. Conventionally, two approaches are provided in order to avoid the problem of losing the touch pen. The first approach uses a physical rope. A first end of the physical rope is connected with the touch pen, and a second end of the physical rope is connected with the touch device. Although the first approach can avoid the problem of losing the touch pen, the appearance is not aesthetically pleasing.
A second approach is a warning method for reminding the user that the touch pen is lost. The warning method is disclosed in Chinese Patent No. CN101692183 for example. The touch device disclosed in Chinese Patent No. CN101692183 comprises a touch pen slot for accommodating the touch pen. Firstly, the warning method detects whether the touch pen is separated from the touch pen slot in order to judge whether the touch pen is well stored. If the touch pen is separated from the touch pen slot, the warning method starts to count time. Then, the warning method comprises a step of judging whether the touch pen is contacted with a touch screen of the touch device in a preset time interval. If the touch pen is not contacted with a touch screen of the touch device, the warning method comprises a step of judging whether the touch pen is contacted with the touch pen slot. If the touch pen is not contacted with the touch pen slot, the touch device warns the user that the touch pen is lost. The warning method, however, still has some drawbacks. For example, after the touch pen is used, if the touch pen is not stored within the touch pen slot but placed beside the touch device, the touch device still issues the warning message. Under this circumstance, the erroneous judgment occurs. The erroneous judgment may confuse the user.
Therefore, there is a need of providing an improved touch device warning method in order to avoid occurrence of erroneous judgment.